DOCSLIB.ORG

Mutations M287L and Q266I in the Glycine Receptor 1 Subunit

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Mutations M287L and Q266I in the Glycine Receptor 1 Subunit Mutations M287L and Q266I in the Glycine Receptor ␣1 Subunit Change Sensitivity to Volatile Anesthetics in Oocytes and Neurons, but Not the Minimal Alveolar Concentration in Knockin Mice Cecilia M. Borghese, Ph.D.,* Wei Xiong, Ph.D.,† S. Irene Oh, B.S.,‡ Angel Ho, B.S.,§ S. John Mihic, Ph.D.,ʈ Li Zhang, M.D.,# David M. Lovinger, Ph.D.,** Gregg E. Homanics, Ph.D.,†† Edmond I. Eger 2nd, M.D.,‡‡ R. Adron Harris, Ph.D.§§ Downloaded from http://pubs.asahq.org/anesthesiology/article-pdf/117/4/765/257527/0000542-201210000-00019.pdf by guest on 01 October 2021 ABSTRACT What We Already Know about This Topic • Inhibitory spinal glycine receptor function is enhanced by vol- Background: Volatile anesthetics (VAs) alter the function of atile anesthetics, making this a leading candidate for their key central nervous system proteins but it is not clear which, immobilizing effect • ␣ if any, of these targets mediates the immobility produced by Point mutations in the 1 subunit of glycine receptors have been identified that increase or decrease receptor potentiation VAs in the face of noxious stimulation. A leading candidate is by volatile anesthetics the glycine receptor, a ligand-gated ion channel important for spinal physiology. VAs variously enhance such function, and blockade of spinal glycine receptors with strychnine af- fects the minimal alveolar concentration (an anesthetic What This Article Tells Us That Is New • EC50) in proportion to the degree of enhancement. Mice harboring specific mutations in their glycine receptors Methods: We produced single amino acid mutations into that increased or decreased potentiation by volatile anesthetic ␣ in vitro did not have significantly altered changes in anesthetic the glycine receptor 1 subunit that increased (M287L, third potency in vivo transmembrane region) or decreased (Q266I, second trans- • These findings indicate that this glycine receptor does not me- membrane region) sensitivity to isoflurane in recombinant diate anesthetic immobility, and that other targets must be receptors, and introduced such receptors into mice. The re- considered sulting knockin mice presented impaired glycinergic trans- mission, but heterozygous animals survived to adulthood, * Research Associate, ʈ Associate Professor, §§ Professor, The and we determined the effect of isoflurane on glycine-evoked University of Texas at Austin, Waggoner Center for Alcohol and responses of brainstem neurons from the knockin mice, and Addiction Research, Austin, Texas. † Research Fellow, # Medical Officer, ** Laboratory Chief, Laboratory for Integrative Neurosci- the minimal alveolar concentration for isoflurane and other ence, National Institute on Alcohol Abuse and Alcoholism, National VAs in the immature and mature knockin mice. Institutes of Health, Rockville, Maryland. ‡ Staff Research Associate, Results: Studies of glycine-evoked currents in brainstem ‡‡ Professor Emeritus, Department of Anesthesia and Perioperative Care, University of California San Francisco, San Francisco, Califor- neurons from knockin mice confirmed the changes seen with nia. § Staff Research Assistant, Diabetes Center, University of Cali- recombinant receptors. No increases in the minimal alveolar fornia San Francisco. †† Professor, Departments of Anesthesiology concentration were found in knockin mice, but the minimal and Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania. alveolar concentration for isoflurane and enflurane (but not Received from the Waggoner Center for Alcohol and Addiction halothane) decreased in 2-week-old Q266I mice. This Research, The University of Texas at Austin, Austin, Texas. Submit- change is opposite to the one expected for a mutation that ted for publication October 10, 2011. Accepted for publication June decreases the sensitivity to volatile anesthetics. 7, 2012. Supported by grant nos. 1PO1GM47818 and AA06399 from the National Institutes of Health, Bethesda, Maryland. Drs. Xiong, Conclusion: Taken together, these results indicate that gly- Zhang, and Lovinger acknowledge support from the Division of cine receptors containing the ␣1 subunit are not likely to be Intramural Clinical and Biomedical Research, National Institute on crucial for the action of isoflurane and other VAs. Alcohol Abuse and Alcoholism, National Institutes of Health, Rock- ville, Maryland. Address correspondence to Dr. Harris: The University of PRESENT consensus suggests that volatile anesthetics Texas at Austin, Waggoner Center for Alcohol and Addiction (VAs) bind to proteins to produce their effects, includ- Research, 1 University Station A4800, Austin, Texas 78712-0159. A 1 [email protected]. Information on purchasing reprints may ing immobility. The key question is, “Which proteins?” The be found at www.anesthesiology.org or on the masthead page at list of candidates is short.1–3 A top candidate is the glycine the beginning of this issue. ANESTHESIOLOGY’s articles are made receptor (GlyR). freely accessible to all readers, for personal use only, 6 months from the cover date of the issue. Evidence for the GlyR as a target for VA includes their Copyright © 2012, the American Society of Anesthesiologists, Inc. Lippincott localization and sensitivity to VAs. The RNAs encoding the 4 Williams & Wilkins. Anesthesiology 2012; 117:765–71 GlyR subunits are mostly in the spinal cord and brainstem, Anesthesiology, V 117 • No 4 765 October 2012 Glycine Receptors and Anesthesia and the spinal cord mediates the immobility effect of VA.5 in 50% of test subjects) of anesthetics in wild-type and Moreover, anesthetic concentrations of VAs substantially en- knockin mice. hance inhibitory currents through the GlyR, both in heter- ologous systems6–8 and neurons.8 More direct evidence Materials and Methods arises from the use of strychnine, a competitive GlyR-specific Knockin mouse production and the electrophysiological antagonist, both at the neuronal and whole animal level. The techniques were described in detail in Borghese et al.21 We application of halothane to decerebrate rats depressed the briefly describe them here, and add pertinent details. The spinal cord sensory neuronal activity to noxious stimuli; experimental work on animals conformed to the guidelines the concurrent application of strychnine partially reversed laid out in the Guide for the Care and Use of Laboratory the halothane-induced depression.9 Sevoflurane reduced Animals, and approval of the corresponding institutional spontaneous action potential firing of ventral horn interneu- Animal Care Committees was obtained. Downloaded from http://pubs.asahq.org/anesthesiology/article-pdf/117/4/765/257527/0000542-201210000-00019.pdf by guest on 01 October 2021 rons in cultured spinal cord tissue slices; application of Electrophysiology in Xenopus Oocytes strychnine decreased the sevoflurane effect.10 Intrathecal ad- Chloroform was purchased from Sigma-Aldrich (Saint ministration of strychnine increased the minimal alveolar Louis, MO), and isoflurane was purchased from Marsam concentration (MAC) of isoflurane.11 The magnitude of Pharmaceuticals (Cherry Hill, NJ). Isoflurane and chloro- GlyR potentiation expressed in oocytes varies according to 12 form solutions were prepared in buffer immediately before the VA used. Intrathecal administration of strychnine to application. rats anesthetized with halothane, isoflurane, or cyclopropane Manually isolated oocytes from Xenopus laevis frogs were increased MAC in proportion to the enhancement of GlyRs injected in the nuclei with complementary DNA encoding observed in vitro13. Furthermore, intrathecal glycine reduced ␣ 14 wild-type and mutated human 1 GlyR subunits. After 1–5 the isoflurane MAC in rats. These results are compatible days, recordings were carried out using the whole cell two- with the hypothesis that GlyRs partly mediate the capacity of electrode voltage clamp configuration. All drugs were ap- VAs to produce immobility. plied by bath-perfusion and solutions were prepared the day ␥ Construction of chimeric glycine- -aminobutyric acid of the experiment. To study the chloroform (1 mM) and type A receptors (GABAA-Rs) allowed the identification of isoflurane (0.3 mM) modulation of glycine currents, the gly- transmembrane amino acids crucial to the VAs’ action, cine concentration equivalent to 5% of the maximal glycine- namely S267 and A288 in the second and third GlyR trans- evoked current (EC5) was determined after applying the gly- 15 membrane domains. Mutation of S267 to cysteine and cine concentration that produced maximal current (3 mM for subsequent labeling with thiol-specific reagents blocked the wild-type, 10 mM for mutant). Glycine was removed with a VA potentiation of GlyRs.16,17 Furthermore, a crystal struc- washout of 5 min between all applications, except after ap- ture of a prokaryotic protein closely related to GlyR was plication of maximal glycine concentrations (15 min). After obtained in the presence of VAs and showed selective bind- two applications of EC5 glycine, each of the modulators was ing of the anesthetics to the regions proposed in the earlier preapplied for 1 min and then coapplied with glycine for 18 studies of GlyR. 30 s. EC5 glycine was applied between coapplication of gly- The identification of a mutation in a receptor that renders cine and modulator. The concentrations of isoflurane and it insensitive or hypersensitive to modulation by VAs would chloroform were chosen as equivalent to1xMAC.22 All allow construction of a knockin mouse that could be tested experiments shown include
Load more

Recommended publications
  • Electrophysiologic Evidence for Increased Endogenous Gabaergic but Not Glycinergic Inhibitory Tone in the Rat Spinal Nerve Ligation Model of Neuropathy Vesa K
    Anesthesiology 2001; 94:333–9 © 2001 American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins, Inc. Electrophysiologic Evidence for Increased Endogenous GABAergic but Not Glycinergic Inhibitory Tone in the Rat Spinal Nerve Ligation Model of Neuropathy Vesa K. Kontinen, M.D., Ph.D.,* Louise C. Stanfa, Ph.D.,† Amlan Basu,‡ Anthony H. Dickenson, Ph.D.§ Background: Changes in the inhibitory activity mediated by There is evidence that both GABA and glycinergic inter- ␥-aminobutyric acid (GABA) and glycine, acting at spinal GABA A neurons are preferentially associated with the control of receptors and strychnine-sensitive glycine receptors, are of in- 6–9 terest in the development of neuropathic pain. There is ana- low-threshold afferent input to the spinal cord. Con- Downloaded from http://pubs.asahq.org/anesthesiology/article-pdf/94/2/333/402482/0000542-200102000-00024.pdf by guest on 29 September 2021 tomic evidence for changes in these transmitter systems after sistent with this, intrathecal administration of the 10 nerve injuries, and blocking either GABAA or glycine receptors GABAA-receptor antagonist bicuculline or the glycine- has been shown to produce allodynia-like behavior in awake receptor antagonist strychnine10,11 produces segmen- normal animals. tally localized tactile allodynia-like behavior in conscious Methods: In this study, the possible changes in GABAergic and glycinergic inhibitory activity in the spinal nerve ligation rats and increased responses to mechanical stimulation 12 model of neuropathic pain were studied by comparing the in anesthetized cats. Intrathecal strychnine has also effects of the GABAA-receptor antagonist bicuculline and the been shown to produce in anesthetized rats reflex re- glycine-receptor antagonist strychnine in neuropathic rats to sponses similar to those produced by nociceptive stim- their effects in sham-operated and nonoperated control rats.
    [Show full text]
  • Ivermectin Interacts with an Intersubunit Transmembrane Domain of the Glycine Receptor T
    Ivermectin interacts with an intersubunit transmembrane domain of the glycine receptor T. Lynagh, T.I. Webb and J.W.Lynch, Queensland Brain Institute,Building 79, The University of Queensland, St Lucia, QLD 4072, Australia. Ivermectin is a widely-used anti-parasitic drug that is effective against nematodes and insects. It paralyses and starves nematodes by activating inhibitory currents at glutamate-gated chloride channels (GluCl). It also activates other members of the Cys-loop ligand-gated ion channel superfamily including the human glycine receptors (GlyR). The location of the ivermectin binding site on these receptors is not known. Homomeric and heteromeric Cys-loop receptors are formed by fivesubunits that each contain a large N-terminal ligand-binding domain and four membrane-spanning helices (M1-M4). Werecently showed that ivermectin sensitivity at GluCls and GlyRs depends on the amino acid identity at a particular location in the third transmembrane (M3) domain (GlyR Ala288). Wehypothesized that tryptophan substitution of residues vicinal to Ala288 might also impair activation by ivermectin and provide a structural basis for understanding the binding interaction between iv ermectin and GlyR. We used site-directed mutagenesis to generate several GlyRs containing a bulkytryptophan residue in a domain formed by M3 (including Ala288) from one subunit and M1 from an adjacent subunit, according to the high-resolution structures of analogous proteins. HEK-293 cells were transfected with wild-type (WT) or mutant GlyR DNAand sensitivity to ivermectin was measured by recording ivermectin-mediated current magnitudes using whole cell patch clamp recording. Several mutants showed 2-4-fold shifts in EC50 values for activation by ivermectin.
    [Show full text]
  • A Potential Approach for Treating Pain by Augmenting Glycine-Mediated Spinal Neurotransmission and Blunting Central Nociceptive Signaling
    biomolecules Review Inhibition of Glycine Re-Uptake: A Potential Approach for Treating Pain by Augmenting Glycine-Mediated Spinal Neurotransmission and Blunting Central Nociceptive Signaling Christopher L. Cioffi Departments of Basic and Clinical Sciences and Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Albany, NY 12208, USA; christopher.cioffi@acphs.edu; Tel.: +1-518-694-7224 Abstract: Among the myriad of cellular and molecular processes identified as contributing to patho- logical pain, disinhibition of spinal cord nociceptive signaling to higher cortical centers plays a critical role. Importantly, evidence suggests that impaired glycinergic neurotransmission develops in the dorsal horn of the spinal cord in inflammatory and neuropathic pain models and is a key maladaptive mechanism causing mechanical hyperalgesia and allodynia. Thus, it has been hypothesized that pharmacological agents capable of augmenting glycinergic tone within the dorsal horn may be able to blunt or block aberrant nociceptor signaling to the brain and serve as a novel class of analgesics for various pathological pain states. Indeed, drugs that enhance dysfunctional glycinergic transmission, and in particular inhibitors of the glycine transporters (GlyT1 and GlyT2), are generating widespread + − interest as a potential class of novel analgesics. The GlyTs are Na /Cl -dependent transporters of the solute carrier 6 (SLC6) family and it has been proposed that the inhibition of them presents a Citation: Cioffi, C.L. Inhibition of possible mechanism
    [Show full text]
  • Unnamed Document
    Mutations M287L and Q266I in the Glycine Receptor ␣1 Subunit Change Sensitivity to Volatile Anesthetics in Oocytes and Neurons, but Not the Minimal Alveolar Concentration in Knockin Mice Cecilia M. Borghese, Ph.D.,* Wei Xiong, Ph.D.,† S. Irene Oh, B.S.,‡ Angel Ho, B.S.,§ S. John Mihic, Ph.D.,ʈ Li Zhang, M.D.,# David M. Lovinger, Ph.D.,** Gregg E. Homanics, Ph.D.,†† Edmond I. Eger 2nd, M.D.,‡‡ R. Adron Harris, Ph.D.§§ ABSTRACT What We Already Know about This Topic • Inhibitory spinal glycine receptor function is enhanced by vol- Background: Volatile anesthetics (VAs) alter the function of atile anesthetics, making this a leading candidate for their key central nervous system proteins but it is not clear which, immobilizing effect if any, of these targets mediates the immobility produced by • Point mutations in the ␣1 subunit of glycine receptors have been identified that increase or decrease receptor potentiation VAs in the face of noxious stimulation. A leading candidate is by volatile anesthetics the glycine receptor, a ligand-gated ion channel important for spinal physiology. VAs variously enhance such function, and blockade of spinal glycine receptors with strychnine af- fects the minimal alveolar concentration (an anesthetic What This Article Tells Us That Is New EC50) in proportion to the degree of enhancement. • Mice harboring specific mutations in their glycine receptors Methods: We produced single amino acid mutations into that increased or decreased potentiation by volatile anesthetic in vitro did not have significantly altered changes in anesthetic the glycine receptor ␣1 subunit that increased (M287L, third potency in vivo transmembrane region) or decreased (Q266I, second trans- • These findings indicate that this glycine receptor does not me- membrane region) sensitivity to isoflurane in recombinant diate anesthetic immobility, and that other targets must be receptors, and introduced such receptors into mice.
    [Show full text]
  • GABA Receptors
    D Reviews • BIOTREND Reviews • BIOTREND Reviews • BIOTREND Reviews • BIOTREND Reviews Review No.7 / 1-2011 GABA receptors Wolfgang Froestl , CNS & Chemistry Expert, AC Immune SA, PSE Building B - EPFL, CH-1015 Lausanne, Phone: +41 21 693 91 43, FAX: +41 21 693 91 20, E-mail: [email protected] GABA Activation of the GABA A receptor leads to an influx of chloride GABA ( -aminobutyric acid; Figure 1) is the most important and ions and to a hyperpolarization of the membrane. 16 subunits with γ most abundant inhibitory neurotransmitter in the mammalian molecular weights between 50 and 65 kD have been identified brain 1,2 , where it was first discovered in 1950 3-5 . It is a small achiral so far, 6 subunits, 3 subunits, 3 subunits, and the , , α β γ δ ε θ molecule with molecular weight of 103 g/mol and high water solu - and subunits 8,9 . π bility. At 25°C one gram of water can dissolve 1.3 grams of GABA. 2 Such a hydrophilic molecule (log P = -2.13, PSA = 63.3 Å ) cannot In the meantime all GABA A receptor binding sites have been eluci - cross the blood brain barrier. It is produced in the brain by decarb- dated in great detail. The GABA site is located at the interface oxylation of L-glutamic acid by the enzyme glutamic acid decarb- between and subunits. Benzodiazepines interact with subunit α β oxylase (GAD, EC 4.1.1.15). It is a neutral amino acid with pK = combinations ( ) ( ) , which is the most abundant combi - 1 α1 2 β2 2 γ2 4.23 and pK = 10.43.
    [Show full text]
  • Environmental Properties of Chemicals Volume 2
    1 t ENVIRONMENTAL 1 PROTECTION Esa Nikunen . Riitta Leinonen Birgit Kemiläinen • Arto Kultamaa Environmental properties of chemicals Volume 2 1 O O O O O O O O OO O OOOOOO Ol OIOOO FINNISH ENVIRONMENT INSTITUTE • EDITA Esa Nikunen e Riitta Leinonen Birgit Kemiläinen • Arto Kultamaa Environmental properties of chemicals Volume 2 HELSINKI 1000 OlO 00000001 00000000000000000 Th/s is a second revfsed version of Environmental Properties of Chemica/s, published by VAPK-Pub/ishing and Ministry of Environment, Environmental Protection Department as Research Report 91, 1990. The pubiication is also available as a CD ROM version: EnviChem 2.0, a PC database runniny under Windows operating systems. ISBN 951-7-2967-2 (publisher) ISBN 952-7 1-0670-0 (co-publisher) ISSN 1238-8602 Layout: Pikseri Julkaisupalvelut Cover illustration: Jussi Hirvi Edita Ltd. Helsinki 2000 Environmental properties of chemicals Volume 2 _____ _____________________________________________________ Contents . VOLUME ONE 1 Contents of the report 2 Environmental properties of chemicals 3 Abbreviations and explanations 7 3.1 Ways of exposure 7 3.2 Exposed species 7 3.3 Fffects________________________________ 7 3.4 Length of exposure 7 3.5 Odour thresholds 8 3.6 Toxicity endpoints 9 3.7 Other abbreviations 9 4 Listofexposedspecies 10 4.1 Mammais 10 4.2 Plants 13 4.3 Birds 14 4.4 Insects 17 4.5 Fishes 1$ 4.6 Mollusca 22 4.7 Crustaceans 23 4.8 Algae 24 4.9 Others 25 5 References 27 Index 1 List of chemicals in alphabetical order - 169 Index II List of chemicals in CAS-number order
    [Show full text]
  • Targeting Glycine Reuptake in Alcohol Seeking and Relapse
    JPET Fast Forward. Published on January 24, 2018 as DOI: 10.1124/jpet.117.244822 This article has not been copyedited and formatted. The final version may differ from this version. TITLE PAGE Targeting Glycine Reuptake in Alcohol Seeking and Relapse Valentina Vengeliene, Martin Roßmanith, Tatiane T. Takahashi, Daniela Alberati, Berthold Behl, Anton Bespalov, Rainer Spanagel Downloaded from The primary laboratory of origin: Institute of Psychopharmacology, Central Institute of jpet.aspetjournals.org Mental Health, Faculty of Medicine Mannheim, Heidelberg University, Germany; at ASPET Journals on September 30, 2021 VV, MR, TTT, RS: Institute of Psychopharmacology, Central Institute of Mental Health, Faculty of Medicine Mannheim, Heidelberg University, Germany; DA: Roche Pharma Research and Early Development, Neuroscience, Ophthalmology and Rare Diseases, Roche Innovation Center Basel, CH-4070 Basel, Switzerland; BB, AB: Department of Neuroscience Research, AbbVie Deutschland GmbH & Co. KG, Ludwigshafen, Germany; AB: Department of Psychopharmacology, Pavlov Medical University, St Petersburg, Russia JPET #244822 JPET Fast Forward. Published on January 24, 2018 as DOI: 10.1124/jpet.117.244822 This article has not been copyedited and formatted. The final version may differ from this version. RUNNING TITLE GlyT1 in Alcohol Seeking and Relapse Corresponding author with complete address: Valentina Vengeliene, Institute of Psychopharmacology, Central Institute of Mental Health (CIMH), J5, 68159 Mannheim, Germany Email: [email protected], phone: +49-621-17036261; fax: +49-621- Downloaded from 17036255 jpet.aspetjournals.org The number of text pages: 33 Number of tables: 0 Number of figures: 6 Number of references: 44 at ASPET Journals on September 30, 2021 Number of words in the Abstract: 153 Number of words in the Introduction: 729 Number of words in the Discussion: 999 A recommended section assignment to guide the listing in the table of content: Drug Discovery and Translational Medicine 2 JPET #244822 JPET Fast Forward.
    [Show full text]
  • Toxicological and Pharmacological Profile of Amanita Muscaria (L.) Lam
    Pharmacia 67(4): 317–323 DOI 10.3897/pharmacia.67.e56112 Review Article Toxicological and pharmacological profile of Amanita muscaria (L.) Lam. – a new rising opportunity for biomedicine Maria Voynova1, Aleksandar Shkondrov2, Magdalena Kondeva-Burdina1, Ilina Krasteva2 1 Laboratory of Drug metabolism and drug toxicity, Department “Pharmacology, Pharmacotherapy and Toxicology”, Faculty of Pharmacy, Medical University of Sofia, Bulgaria 2 Department of Pharmacognosy, Faculty of Pharmacy, Medical University of Sofia, Bulgaria Corresponding author: Magdalena Kondeva-Burdina ([email protected]) Received 2 July 2020 ♦ Accepted 19 August 2020 ♦ Published 26 November 2020 Citation: Voynova M, Shkondrov A, Kondeva-Burdina M, Krasteva I (2020) Toxicological and pharmacological profile of Amanita muscaria (L.) Lam. – a new rising opportunity for biomedicine. Pharmacia 67(4): 317–323. https://doi.org/10.3897/pharmacia.67. e56112 Abstract Amanita muscaria, commonly known as fly agaric, is a basidiomycete. Its main psychoactive constituents are ibotenic acid and mus- cimol, both involved in ‘pantherina-muscaria’ poisoning syndrome. The rising pharmacological and toxicological interest based on lots of contradictive opinions concerning the use of Amanita muscaria extracts’ neuroprotective role against some neurodegenerative diseases such as Parkinson’s and Alzheimer’s, its potent role in the treatment of cerebral ischaemia and other socially significant health conditions gave the basis for this review. Facts about Amanita muscaria’s morphology, chemical content, toxicological and pharmacological characteristics and usage from ancient times to present-day’s opportunities in modern medicine are presented. Keywords Amanita muscaria, muscimol, ibotenic acid Introduction rica, the genus had an ancestral origin in the Siberian-Be- ringian region in the Tertiary period (Geml et al.
    [Show full text]
  • Strychnine Poisoning
    0++- Poison HOTLINE Partnership between UnityPoint Health and University of Iowa Hospitals and Clinics November 2013 Strychnine Poisoning Strychnine is a chemical naturally found in the seeds of the tree Strychnos nux- vomica. It is mainly used as a pesticide to control rats, moles, gophers, and coyotes. Commercial baits are pelleted and often dyed red or green. Strychnine has on rare occasions been found to be mixed with street drugs such as LSD, heroin, and cocaine. Strychnine is a white, odorless, bitter tasting crystalline powder that can be taken by mouth, inhaled or given intravenously. Strychnine is highly toxic and Did you know …… only a small amount is needed to produce severe health effects in people. As little as 30 mg may cause death in an adult. Vaporizing alcohol and “smoking” the vapors (inhaling Strychnine blocks the action of the neurotransmitter glycine which controls how is a more accurate term) is a nerve signals are sent to muscles. Glycine is an inhibitory neurotransmitter and new method for alcohol works like an “off switch” for muscles. When this “off switch” is not working consumption. The alcohol is because it is being blocked by strychnine, muscles throughout the body have poured into a vaporizing severe, painful spasms. While these spasms may look like the patient is having machine or over dry ice and a seizure, it is not a true seizure and there is no post-ictal phase. Repetitive inhaled. The alcohol enters muscle spasms caused by strychnine will lead to fever, muscle break down the lungs where it is rapidly (rhabdomyolysis), severe metabolic acidosis and respiratory failure.
    [Show full text]
  • A Systematic Review on Main Chemical Constituents of Papaver Bracteatum
    Journal of Medicinal Plants A Systematic Review on Main Chemical Constituents of Papaver bracteatum Soleymankhani M (Ph.D. student), Khalighi-Sigaroodi F (Ph.D.)*, Hajiaghaee R (Ph.D.), Naghdi Badi H (Ph.D.), Mehrafarin A (Ph.D.), Ghorbani Nohooji M (Ph.D.) Medicinal Plants Research Center, Institute of Medicinal Plants, ACECR, Karaj, Iran * Corresponding author: Medicinal Plants Research Center, Institute of Medicinal Plants, ACECR, P.O.Box: 33651/66571, Karaj, Iran Tel: +98 - 26 - 34764010-9, Fax: +98 - 26-34764021 E-mail: [email protected] Received: 17 April 2013 Accepted: 12 Oct. 2014 Abstract Papaver bracteatum Lindly (Papaveraceae) is an endemic species of Iran which has economic importance in drug industries. The main alkaloid of the plant is thebaine which is used as a precursor of the semi-synthetic and synthetic compounds including codeine and naloxone, respectively. This systematic review focuses on main component of Papaver bracteatum and methods used to determine thebaine. All studies which assessed the potential effect of the whole plant or its extract on clinical or preclinical studies were reviewed. In addition, methods for determination of the main components, especially thebaine, which have been published from 1948 to March 2013, were included. Exclusion criteria were agricultural studies that did not assess. This study has listed alkaloids identified in P. bracteatum which reported since 1948 to 2013. Also, the biological activities of main compounds of Papaver bracteatum including thebaine, isothebaine, (-)-nuciferine have been reviewed. As thebaine has many medicinal and industrial values, determination methods of thebaine in P. bracteatum were summarized. The methods have being used for determination of thebaine include chromatographic (HPLC, GC and TLC) and non chromatographic methods.
    [Show full text]
  • Molecular Basis of the Alternative Recruitment of GABAA Versus Glycine Receptors Through Gephyrin
    ARTICLE Received 19 Aug 2014 | Accepted 4 Nov 2014 | Published 22 Dec 2014 DOI: 10.1038/ncomms6767 Molecular basis of the alternative recruitment of GABAA versus glycine receptors through gephyrin Hans Michael Maric1,2,*, Vikram Babu Kasaragod1,*, Torben Johann Hausrat3, Matthias Kneussel3, Verena Tretter4, Kristian Strømgaard2 & Hermann Schindelin1 g-Aminobutyric acid type A and glycine receptors (GABAARs, GlyRs) are the major inhibitory neurotransmitter receptors and contribute to many synaptic functions, dysfunctions and human diseases. GABAARs are important drug targets regulated by direct interactions with the scaffolding protein gephyrin. Here we deduce the molecular basis of this interaction by chemical, biophysical and structural studies of the gephyrin–GABAAR a3 complex, revealing that the N-terminal region of the a3 peptide occupies the same binding site as the GlyR b subunit, whereas the C-terminal moiety, which is conserved among all synaptic GABAAR a subunits, engages in unique interactions. Thermodynamic dissections of the gephyrin– receptor interactions identify two residues as primary determinants for gephyrin’s subunit preference. This first structural evidence for the gephyrin-mediated synaptic accumulation of GABAARs offers a framework for future investigations into the regulation of inhibitory synaptic strength and for the development of mechanistically and therapeutically relevant compounds targeting the gephyrin–GABAAR interaction. 1 Rudolf Virchow Center for Experimental Biomedicine, University of Wu¨rzburg, Josef-Schneider-Strae 2, Building D15, D-97080 Wu¨rzburg, Germany. 2 Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark. 3 Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, D-20251 Hamburg, Germany. 4 Department of General Anesthesia and Intensive Care, Medical University Vienna, Wa¨hringer Gu¨rtel 18-20, 1090 Vienna, Austria.
    [Show full text]
  • Increased NMDA Receptor Inhibition at an Increased Sevoflurane MAC Robert J Brosnan* and Roberto Thiesen
    Brosnan and Thiesen BMC Anesthesiology 2012, 12:9 http://www.biomedcentral.com/1471-2253/12/9 RESEARCH ARTICLE Open Access Increased NMDA receptor inhibition at an increased Sevoflurane MAC Robert J Brosnan* and Roberto Thiesen Abstract Background: Sevoflurane potently enhances glycine receptor currents and more modestly decreases NMDA receptor currents, each of which may contribute to immobility. This modest NMDA receptor antagonism by sevoflurane at a minimum alveolar concentration (MAC) could be reciprocally related to large potentiation of other inhibitory ion channels. If so, then reduced glycine receptor potency should increase NMDA receptor antagonism by sevoflurane at MAC. Methods: Indwelling lumbar subarachnoid catheters were surgically placed in 14 anesthetized rats. Rats were anesthetized with sevoflurane the next day, and a pre-infusion sevoflurane MAC was measured in duplicate using a tail clamp method. Artificial CSF (aCSF) containing either 0 or 4 mg/mL strychnine was then infused intrathecally at 4 μL/min, and the post-infusion baseline sevoflurane MAC was measured. Finally, aCSF containing strychnine (either 0 or 4 mg/mL) plus 0.4 mg/mL dizocilpine (MK-801) was administered intrathecally at 4 μL/min, and the post- dizocilpine sevoflurane MAC was measured. Results: Pre-infusion sevoflurane MAC was 2.26%. Intrathecal aCSF alone did not affect MAC, but intrathecal strychnine significantly increased sevoflurane requirement. Addition of dizocilpine significantly decreased MAC in all rats, but this decrease was two times larger in rats without intrathecal strychnine compared to rats with intrathecal strychnine, a statistically significant (P < 0.005) difference that is consistent with increased NMDA receptor antagonism by sevoflurane in rats receiving strychnine.
    [Show full text]